I do not have doubts kind stuuf on the insufficient duration of the 9v batteries and their high price, but the problem is not that one, that was my intention to resolve, I has thought simply on the reduced dimensions how much more is possible, and said is to us successful, however I will construct an other nimh batteries charger to only render happy you, promised.

I've seen a lot of 9v-powered cell phone chargers, but I always wondered how much energy you can really get out of one battery and whether that makes them economical at all. Since the battery will only give you 400mAh at best, and the linear regulator doesn't stretch that any further, it seems like something with NiMH cells would be a lot cheaper than half a phone charge from a $4 battery.

There could be a short in your circuit or you are drawn more than 1.5 amp. If you are drawing more than 1.5amp there a couple of things to do increase your size of your heatsink or putting in a current bypass transistor. http://www.fairchildsemi.com/ds/LM/LM7805.pdf go to pg 28 of 48 they show how to wire up a current bypass transistor.

Yeah, these are mostly pocket sized emergency chargers for me. Those Ultra M3's have about 600mAh if I remember right, but they could be used more than that (to reach voltage of 7v) in this kind of usage. But still, cell phone batteries are what... 650 - couple of thousands mAhs, so max one charge. These are good for ipods. Apple has made really good job with power management in ipods. 350mAh battery can get over 10h of music. One good 9v battery could get almost two full charges. Thanks Stuuf for your post, that made me rethink my incoming instructable. I was going to make smaller charger, but now I might do something else... Might still be smaller, though.

I do not have doubts kind stuuf on the insufficient duration of the 9v batteries and their high price, but the problem is not that one, that was my intention to resolve, I has thought simply on the reduced dimensions how much more is possible, and said is to us successful, however I will construct an other nimh batteries charger to only render happy you, promised.

well i decided to throw one together seeing as i had a dead 9V battery and the rest of the bits at hand. will definitely come in useful. I also enclosed it more with epoxy putty and the plastic base from the battery for a neater finish.

I'll take this instructable as a challenge! Looks good to me. You gave couple of pics, to determine the pinout, many pics of the final device... I personally would have added capacitors to regulators out- and input, but usually 78**s work without.